Emerson Rosemount 928, Reference Manual

Page: 50 / 204

6. Select
OK
to accept the current date as the calibration date and continue.
7. Acknowledge the warning. If necessary, remove the loop from automatic control.
Note
Calibration of an O
2
sensor is unlikely to use a true zero value for its lower limit; one
must calibrate the sensor to a known lower percent oxygen value (such as 15
percent oxygen level by volume) in order to "zero" the sensor as outlined in the
remainder of the calibration steps below.
8. When calibrating for H
2
S and CO, expose the sensor to clean air to zero the reading.
When calibrating for O
2
, expose the sensor to a known percent of oxygen content
calibration gas (recommended 15 percent oxygen by volume) to be used as the
"zero" calibration value. If the ambient air may contain trace amounts of target gas
or other gases (for example, carbon monoxide from engine exhaust) that may
interfere with zeroing the device, do the following:
a) Obtain a cylinder of verified clean air (H
2
S and CO) or a cylinder of verified
percent oxygen content calibration gas (O
2
) and a length of calibration
tubing (PVC tubing, 3/16-in. ID, 5/16-in. OD).
Configuration Reference Manual
September 2019 00809-0100-4928
50 Emerson.com/Rosemount